I purchased a nice pair of used Bach rear panniers for commuting and was thinking about getting something a little bigger for the back for touring and using the Bachs on the front. They mount with two hooks on the top and a springy hook on the bottom in a "Y" configuration.

So here's what I'm wondering since I can't find info on these panniers online...

....sometimes manufacturers say "rear only" or "front or rear" in their pannier descriptions. What is the difference between front and rear panniers (besides size, generally)? Is it fine to mount my Bachs and any smallish rear pannier on front rack? Thanks.

"Rear specific" means that from the side its an asymmetric looking bag. The leading lower corner is usually rounded off a bit to provide clearance for shoe heel. And the trailing corner usually has a big pocket, maybe with some rear facing reflective material attached. There's a left and right bag in the pair and you wouldn't want to swap them since they wouldn't fit too well.

Aside from foot clearance issues and fittings there isn't any difference. Some touring radicals put the biggest panniers they can find on front low riders on the theory that most people overload the rear, low riders keep the weight low making the bike more stable and the front wheel is stronger being undished.

Do what works for you, but experiment with different loading regimes because it does make a difference to handling. I find that heavily loading the front wheel makes the wheel floppy and the bike unstable at low speeds, but is very stable at higher speeds.

There was a really interesting article in the Rivendell Reader a few years ago about French camping bikes. The particular bike mentioned had integral welded racks including a rear low rider type. When the bike was loaded with 80lbs of gear it was said to be incredibly stable. This was because the weight was kept very low. Supposedly.

You can always secure loose panniers with webbing gear straps available at most sporting goods stores. Wrap the strap completely around the pannier and rack and tighten it.